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2004 Geobgic Hazard Field Observations <br />Sarlh of Divide Mining Area <br /> <br />4.0 MINING METHOD <br />The longwall mining method will be utilized in the South of Divide mining area The planned <br />panel design is similar to the mined longwall panels in West Elk Aline, where baseline <br />subsidence measruements were performed. The baseline data was then used to project <br />subsidence parameters in the Apache Rocks and Box Canyon mining areas. The combined <br />baseline subsidence data and the mining and subsidence experience gained from nine years of <br />annual observations is used herein to project subsidence parameters and effects for the South of <br />Divide mining area. <br />A range of 8 to 14 feet of coal will be extracted from the E-Seam. Coal extraction thickness of 8, <br />11, 12, and 14 feet are planned for panels El through E4; a thickness of 12 to I4 feet is planned <br />for panels ES through E9. An extraction thickness of 14 feet is predominant in panels El <br />through E4 (particularly in panel E4) and in panels ES through E8, where 12 feet extraction will <br />only be on the easternmost edge of the panels (Map 1). <br />Longwall panels El through E8 are all 1,080 feet wide, and range from about 9,000 to 11,000 <br />feet long. Panel E9 is projected to be 1,080 feet wide and 5,750 feet long. The panels will be <br />mined by the retreat method Panels El through ES will be mined from east to west- Panel E9 <br />will be mined from south to north <br /> <br />The trend of panels El through E8 is approximately N 80° W. Panel E9 trends roughly N 10° E. <br />The overburden depth above panels El through E4 ranges from about 400 to 1,425 feet, whereas <br />the overburden depth ranges from 500 to 1,250 feet in panels ES through E8. The overburden <br />depth ranges in thickness from 500 to 550 feet above panel E9. <br />All longwall panels are planned to be separated by two rows of chain pillars. The row nearest to <br />the headgate side of the panels will be of a rigid pillaz design-on centers 125 feet wide by 200 <br />feet long. The row on the tailgate side of the panel will be of a yield pillar design-on centers 75 <br />831-032.621 Wright Water Engineers, Ina Page 6 <br />November 2004 <br />